A conventional peripheral device for a PC is utilized while being connected directly to a PC via a connecting cable. In this case, the PC is equipped with an authentication means in order to restrict reading/writing of data registered in the PC. The authentication means can establish authentication data that is composed of arbitrary characters for the data in the PC. When a plurality of kinds of data is present, individual authentication data can be established for each data.
In order that the peripheral device for the PC may perform reading/writing of the data in the PC, for which the authentication data is established, it is required to input from an input means in the peripheral device the same authentication data as the authentication data established in the PC. If the input does not agree with the authentication data, the authentication is not authorized, so that the reading/writing with respect to the data cannot be performed.
In addition, the PC and the peripheral device can be connected with each other via a network. In this case, in order to restrict accesses to the PC via a network, the authentication means in the PC can be utilized. In the authentication function, authentication data for connection via a network is established. A user of the peripheral device connecting to the PC via a network must input from the input device the same authentication data as the authentication data having been registered, so as to enable reading/writing with respect to the data in the PC.
The establishing itself of the authentication data in the PC is performed so that arbitrary authentication data is inputted from the input means in the peripheral device via a connecting cable to the PC, and is registered in the PC. Here, if the authentication data has been already established, after authentication for the PC is authorized by inputting from the input device in the peripheral device the same authentication data as the authentication data having been established in the PC, new authentication data 12 can be established.
As an example of a conventional art, there is a technology described in Japanese Patent Laid-Open No. 124308/1998.
According to the technology described in Japanese Patent Laid-Open No. 124308/1998, information such as programs and parameter values required for PC operations is information assets in which know-how for a system owner to operate the system has been accumulated. Because greatest attention must be paid to leakage of data including the information assets to third parties, there is a method in which, in the viewpoint of protection against the leakage of the information assets, instructions for protection are embedded in a program to encrypt instruction words for the PC, whereby the instructions are made invisible to a user having no release key.
[Patent document 1] Japanese Patent Laid-Open No. 124308/1998